Re: Mixing of forward and back slashes in paths?

2015-03-08 Thread sisyphus1
-Original Message- 
From: L. Walsh

Sent: Saturday, March 07, 2015 5:21 PM
To: sisyph...@optusnet.com.au
Cc: Strawberry Perl
Subject: Re: Mixing of forward and back slashes in paths?



And if you do:
$^X = "C:\Strawberry\perl\bin\perl.exe";
I don't do it -- perl does it.  Look at the listing for PERL5LIB at the 
bottom of the report:


The setting of these things are determined by what's in the perl source 
distro and ought therefore be dealt with at the perl source level - so it 
needs to be achieved by patching the perl source (and perhaps some of the 
core modules).
I build perl from source myself - and see the same mixture of forward and 
backward slashes in paths.
I don't see it as being Strawberry's responsibility to deal with this (but I 
have no official position with the Strawberry project).


On Windows 7, I strike occasions where forward slashes are unworkable and 
need to be replaced by backslashes - so I'd be very annoyed if perl were 
ever to forbid the backslash in a path (or automatically convert it to a 
forward slash).


Here's an example of forward slashes being unworkable on my Windows 7 box. 
It relies on the existence of  ../doc.txt.


###
use warnings;
use strict;

my $f1 = '../doc.txt';
my $f2 = "../doc.txt";
my $f3 = '..\doc.txt';
my $f4 = "..\\doc.txt";

# will fail
warn "failed to copy $f1 to dac.txt"
 if system 'copy', $f1, 'dac.txt';

# will fail
warn "failed to copy $f2 to dec.txt"
 if system 'copy', $f2, 'dec.txt';

# will succeed
warn "failed to copy $f3 to dic.txt"
 if system 'copy', $f3, 'dic.txt';

# will succeed
warn "failed to copy $f4 to duc.txt"
 if system 'copy', $f4, 'duc.txt';

###

I don't know if the behaviour I see from this script is common.

Even if perl were to convert the backslash to forward slash for display 
purposes only, I would be very annoyed.
If I were to "say $f1;" in the above script, I would expect to see what's 
actually there  - namely "..\doc.txt".


But it's not me you need to convince about this - it's p5p   or kmx (who 
does have an official position with the Strawberry project).


I suspect it's now too late for either p5p or kmx to do anything about this 
for the upcoming 5.22 - maybe take it up in the next round of blead releases 
(5.23) ?


Cheers,
Rob




Re: Mixing of forward and back slashes in paths?

2015-03-08 Thread Rob Dixon

On 07/03/2015 06:21, L. Walsh wrote:

sisyph...@optusnet.com.au wrote:

-Original Message- From: L. Walsh
Sent: Saturday, March 07, 2015 5:00 AM
To: Strawberry Perl
Subject: Mixing of forward and back slashes in paths?


I recently was looking into a CPAN tester report

P-1.1.24:
- MSWin32-x86-multi-thread-64int / 5.20.2:
  - FAIL
http://www.cpantesters.org/cpan/report/bc273757-6c01-1014-a765-afcf632b568b

The last win32 version I'd tested with was a bit ago
@ in 5.14 and it didn't have this problem.


Sorry - I couldn't work out what it is that you're asking about.
And I couldn't spot anything in the testers report that indicates
any problem with any of the paths. Both "\" and "/" are acceptable
(andessentially equivalent) where used (AFAICS).


Not really. In the past on windows, perl has converted 'backslashes'
to forward slashes, because in perl, backslashes are a quote char. As
I pointed out in 5.14, all the paths (that come from perl (@INC,
$^X, PERL5LIB) have had forward slashes used for the path separators
so the Windows version would be as compatible as possible with the
linux versions. Theidea was to to support compatibility.

Now if a *user*, uses '\', then that's on them -- but perl didn't
contribute to the problem.


If you do:
$test = "C:\this";


I wouldn't do that. I'd use $test= "C:/this" because "\" does special
things in perl.


what do you expect to be output by:
printf "%s\n", $test;

And if you do:
$^X = "C:\Strawberry\perl\bin\perl.exe";


I don't do it -- perl does it.  Look at the listing for PERL5LIB at the
bottom of the report:

Built under MSWin32
Compiled at Feb 21 2015 12:36:01
%ENV:
PERL5LIB="C:\cpan\build\Types-Core-0.1.4-8EUNyT/blib/arch;C:\cpan\build\Types-Core-0.1.4-8EUNyT/blib/lib;C:\cpan\build\Xporter-0.1.2-OWKF3Q/blib/arch;C:\cpan\build\Xporter-0.1.2-OWKF3Q/blib/lib;C:\cpan\build\mem-0.4.5-dZP9Gl/blib/arch;C:\cpan\build\mem-0.4.5-dZP9Gl/blib/lib"

...
It has the backslashes in double quotes.  How should anyone expect that
to work?


what do you expect to be output by:
printf "5.20 path for perl: $^X???\n";


The same thing that perl 5.20 prints out -- but in 5.14 it prints
C:/Strawberry/perl/bin/perl.exe" -- which, if you want the best
compatibility in the windows environment for CPAN scripts written
mostly against *nix hosts, would seem to be the wise choice.

That's why I was asking if this incompatibility has been introduced
on purpose or if it has slipped by?  Having the windows version of
perl NOT convert BS's to FS's seem a large break in past
compatibility and *needlessly* causes breaking in CPAN modules that
are largely developed in *nix compatible environments.


I'm not clear exactly what "incompatability* you're referring to, but 
you clearly have some misconceptions.


- Perl has never converted backslashes to forward slashes. It simply
accepts *either* form of slash as path separators in parameters to IO
operators like mkdir, opendir, open, chdir etc. That is primarily to
avoid having to escape (with a second backslash) all of the backslash
separators in a canonical Windows path

- The line

PERL5LIB="C:\cpan\build\Types-Core-0.1.4-8EUNyT/blib ... 
arch;C:\cpan\build\mem-0.4.5-dZP9Gl/blib/lib"


is in *shell* context, and the list is in double quotes to allow for
spaces in any of the path components. If you used the same expression
inside Perl then you wouldn't get the same string, but that is irrelevant

- The PATH environment variable *cannot* use forward slashes as path
separators. It is purely for Windows' purposes, and forward slash is an
illegal character in a Windows path string.

- The issue with backslashes only affects string constants. "C:/this" is
fine because forward slashes aren't special, but "C:\this" won't work
because \t is interpreted as a horizontal tab character within double
quotes. But you can write "C:\\this" or 'C:\this', and they will work
fine when used as IO operator parameters

As I said, I'm not clear where your confusion lies, but I hope this
helps to clear things up.

Rob


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